Hardscaping & Landscaping Blog

Archive for October, 2011

Frequently Asked Questions About Concrete

Monday, October 31st, 2011

What causes concrete to crack?

There are several causes for cracks in concrete. It is vulnerable and reacts to changes in temperature and moisture just as most materials do. They can also result from a poorly planned foundation, improper finishing, or even from not curing the concrete. It is almost inevitable that at some point cracks will form. The following are examples of a couple of the more common causes:

-Shrinkage Cracks: These aptly named cracks occur as the concrete dries. In order to make concrete pourable excess water is added that is later bled out. Thus the initial volume of the concrete is much larger than that of when it has dried. When cracks happen in recently poured concrete it is most often due to dry or windy climates. They cause the surface of the concrete to dry faster than the excess water can seep up to keep it moist, resulting in shrinkage of the concrete and therefore, cracks.

- Crazing Cracks: Crazing cracks are a series of fine cracks that form a pattern across the surface of the concrete. These cracks are similarly caused by a too quickly drying concrete surface. They can be prevented either through immediate curing or else by dampening the base prior to pouring the concrete, thereby reducing the amount of water it will absorb from the concrete and forcing it back up to the surface.

Is there any way to prevent cracks from forming?

Most cracks that form during the construction process can be minimized through finishing and proper curing. Another preventative measure is to use control joints. These joints work by creating weak points in the concrete. If placed correctly they will encourage cracks to form in the joint where we would like them rather than randomly across the concrete. Likewise, isolation joints, joints separating the concrete from a nearby object such as a drain, wall, etc., allow the concrete a space in which to expand or contract. This wiggle room reduces tension, and by default, more cracks.

What is the difference between concrete and cement?

Cement is an ingredient used to make concrete. The cement is what reacts to the water in the mix and becomes the glue of the cement, holding it together and making it strong.

Is there a way to reinforce concrete?

There are a couple of ways to do this. We use rebar for structural reinforcement as well as fiber mesh. The rebar we use is a ½” in diameter and is placed vertically and horizontally in 4 foot sections or smaller, creating a grid pattern. In this way the rebar acts as a sort of skeletal support for the concrete while the fiber mesh aids in preventing cracks from forming. Another option is to use wire mesh, but because fibers are much more lightweight they tend to stay in position better. Fiber mesh also tends to be less expensive, as it requires far less labor to install. By using both the rebar and the fiber mesh we build an effective support system to reinforce your concrete project.

How does the weather affect when concrete can be poured?

Concrete can be poured throughout the year as long as certain measures are taken to compensate for temperature and moisture. Mild, humid days are optimal to prevent the concrete from drying out too quickly and cracking. As the weather gets hotter or drier, pouring concrete becomes more difficult because the moisture necessary for it to harden evaporates too quickly. Alternatively, as the weather gets cooler the concrete will take longer than usual to dry. We can use admixers such as water reducers or accelerators to combat these potential issues. The only time we cannot pour concrete is, of course, when it is raining or freezing.

How do I know how much concrete to use?

The first step is to precisely measure the space we will be pouring in. Once we have these measurements we multiply the length by the width and divide by 81. The resulting number is the amount of concrete we will need to order in cubic yards (the standard measurement by which contractors order concrete).

How do I know what kind of concrete to use?

Concrete is categorized by its strength in pounds per square inch, or PSI. This number means that concrete at a certain PSI is tested to withstand the pressure from a certain amount of weight without crushing. For example, most contractors use between 3000 PSI and 5000 PSI for residential applications such as driveways and garage floors. This means that once such concrete is ready for use it will be able to hold firm underneath more than 3000 to 5000 pounds. We most commonly use 5000 PSI concrete to make sure our projects are built to last.

How long do I have to wait to drive on new concrete?

To allow the concrete ample time to strengthen and harden, we recommend waiting between 10 and 14 days to use concrete driveways or garage floors. 

Can I pour concrete myself?

Of course you can. Just remember that the bigger the project, the more difficulties may arise. Concrete can be finicky to work with, and factors such as heat, humidity, wind, and grade all must be taken into account when you pour. You also need to make sure to use just enough water or else you may face issues down the road. Pouring and finishing concrete is hard work, and often the convenience of hiring a contractor outweighs the enticement of a challenge for most home owners.

Is it ok to use chemical de-icers on my concrete driveway during the winter?

No, we do not recommend ever using such a product on concrete. It can chemically attack and weaken the surface of your driveway, with recently poured concrete being the most susceptible. If absolutely necessary we suggest using a magnesium or potassium based de-icer. They are less damaging to the concrete, though they are still not a great idea. Instead, we recommend home owners keep up with shoveling away any snow, and if need be, using sand to give their vehicles better traction. 

Is there a way to make concrete look more appealing?

Concrete does not need to be a plain, gray slab. There are many options for upgrading your concrete to design a more pleasing look. We can add color directly into the concrete mix or else add a layer over the surface of the concrete to create a more attractive space. In addition to color, we can stamp the concrete to look like brick or stone. Stamped concrete is not only more aesthetically pleasing, but it also helps to disguise any future flaws from being quite as noticeable.

How to Build a Retaining Wall

Wednesday, October 19th, 2011

                Whether you would like to create a flat surface out of a sloped yard or create a raised garden to grow your favorite plants or vegetables, building a retaining wall is as smart as it is useful. There are varying options when it comes to what material or style you would like to achieve, but in this post we will focus on the basics to give you a better understanding of what our process involves. Though the thought of enhancing your yard with such a project may seem daunting, please don’t let that deter you.  Instead, remember that a sturdy landscape retaining wall will completely transform your landscape, turning it into a space that can finally be used to its fullest potential.

                To begin, we create a solid foundation for your retaining wall. We start by digging out a trench that is fourteen inches deep and between eighteen and twenty-four inches wide. This will allow us enough room to both create a strong base and bury the first course of blocks for your wall. We do this because a solid support system is necessary to keep your wall standing upright over time. After the trench is dug we fill the bottom with eight inches of class five gravel and compact it down. We use this material because it is easily compacted and helps to drain water away from your base. The gravel also aids in leveling out the ground beneath your wall and lends itself to supporting a more solid structure.

                After we lay down the first course of blocks we check again that the base of the wall is level. This step is imperative as we need a level base in order to build a level wall. Once we know the first course is level we begin to stagger the landscape blocks and build upwards. We cut one of the blocks in half, and place one half at each end of the wall. We do this for every other course, and this way the joints between the blocks of each course will naturally be staggered from the courses above and below. However, we do not simply build up your wall vertically. The soil behind a retaining wall exerts a great amount of pressure and to counteract this force we step the blocks back towards the soil with each course. The blocks we use have a special feature, a lip at the back of the block which catches against the block below it. In this way we use the pressure from the soil behind the wall to our advantage, as it will now push against the lip of one block and hold it in place against the block below. To finish the blocks we glue down a final course of cap stones, forming a small lip and creating an aesthetically pleasing wall.

                Next, we fill the remaining cavity behind the retaining wall with some of the previously dug up native soil and tamp it down. We then put down a layer of washed rock extending twelve inches behind the wall. Unlike soil, the washed rock will not retain any moisture, meaning that it will not expand and push against your wall in the future. It will further serve to drain any moisture down towards our final critical feature, the drain tile. The drain tile is a perforated tube that runs along one of the lower courses and is sloped down and away from your retaining wall. Once the drain tile is in place we cover it with another twelve inch wide expanse of rock, all the way up to a six-inch gap to the top. The rock is topped off with more of the native soil, thereby giving you the choice to plant or sod over the top of your retaining wall.

                We know that water means movement, and if it is not directed away from your wall, that water will push its way through; along with any soil it can pick up on the way. If left without a place to go water will move the ground around your retaining wall, and over time, even the wall itself. The drain tile will discourage this, and in order to prevent the drain tile from clogging with dirt or debris we cover it with what we call a “sock,” essentially a mesh-like fabric that allows water to seep through but prevents the soil from following. This entire process functions to channel any moisture out of the soil and down to the drain tile, where it is whisked away from your retaining wall.

                Keep in mind that these steps are really just a guideline for what is involved with building a landscape block retaining wall. Before any of the actual construction can take place we make note of several key elements that will determine the scope of work involved with your project. Factors such as slope, size, and soil content are all major influences on your project, not to mention any city or state building requirements.  Rest assured that our experience gives us the skill necessary to provide you with such solutions when constructing your retaining wall. Whether this means incorporating geosynthetic fabric or soil correction techniques, we will make sure to build you a sound, safe retaining wall. In fact, we go above and beyond industry standards to do so, because making our customers happy is what makes us happy.